1. Field of the Invention
This invention relates to a finder optical system for such cameras as videocameras and cinecameras.
2. Description of the Prior Art
In the formation of the conventional finder optical system of this kind, for example, as shown in FIG. 1, a light path is divided by a half-mirror 3 arranged between a photographing lens 1 and photographing relay lens 2 so that an image may be once formed of a part of the light from an object to be photographed on a screen 7 through a relay lens 4, mirror 5 and relay lens 6 and may be magnified by a magnifying lens 8 to be observed. However, there has been a problem that, in such formation, as the half-mirror 3 and relay lens 2 enter the camera body, it is difficult to interchange the lenses. There has been also a problem that, even if only the lens part in front of the half-mirror 3 is to be interchanged, the freedom in the optical design will reduce. Further, in such formation, if the finder magnification is to be raised, the visual angle of the relay lens 4 will become so large as to require a lens as large as the photographing relay lens, resulting in a high cost. Therefore, naturally, there has been a problem that the focal length of the relay lens 4 can not help being made longer and the visual field can not help being made smaller, that is to say, the magnification of the finder system can not help reducing. This problem is also caused by the fact that, as this kind of camera requires a comparatively long space on the photographing device part side, the position of the finder eye point 9 is required to be far from the half-mirror 3.